(a) Field of the Invention
The present invention relates to a sample tray feeding apparatus for the electrophoretic systems, and more specifically to a sample tray feeding apparatus so adapted as to permit recovering excessive samples remaining after analyses.
(b) Description of the Prior Art
Automatic electrophoretic systems use samples trays having such a construction, for example, as shown in FIG. 1. Speaking concretely, the sample tray 1 has plural cavities for containing samples 2. Such sample trays are accommodated in a sample tray accommodating container in a condition where they are filled with samples, and fed consecutively by a sample tray feeding apparatus for applying samples onto a carrier and other purposes. There have conventionally been known sample tray feeding apparatus having such a construction, for example, as shown in FIG. 2. Speaking concretely, the sample tray feeding apparatus shown in FIG. 2 consists of a sample tray accommodating container 3 having inside dimensions nearly equal to the outside dimensions of the sample tray 1 and so designed as to accommodate multiple sample trays 1 in piled-up condition and a piston type sample tray feeding mechanism 6 both of which are mounted on a stand 4, in addition to a sample tray receiving container 7 located beside the stand 4 and used for accommodating sample trays having been used for sample application. Piled up in this sample tray accommodating container are sample trays 1 which have been inserted through an upper opening 3a, and mounted on the sample tray located at the uppermost position is a sample tray protective cover 5.
Therefore, the sample tray 1 located at the uppermost position is covered with the protective cover 5, whereas the other sample trays are covered with the sample trays mounted thereon respectively so as to prevent evaporation of water contents from the samples contained in the sample trays. Further, formed in the lower end of the sample tray accommodating container is a front opening 3b having a size just permitting a single sample tray to pass therethrough at a time. By operating a pushing rod 6a of the sample tray shifting mechanism in the direction indicated by the arrow, the sample tray located at the lowermost position is pushed out of the container 3 through the opening 3b and displaced to the position represented by the reference symbol A. When the pushing rod 6a of the sample tray shifting mechanism 6 is returned to its initial position, the rest sample trays are allowed to go down until the second lowest sample tray is located at the lowermost position. On the other hand, a sample is allowed to adhere to a blade 9 of a sample applicator 8 when it is lowered down. The blade 9 is then lifted up, shifted to the position designated by the reference symbol B and then lowered down once again to apply the sample onto a carrier 10. Successively, when the second sample tray located now at the lowermost position is shifted to the position A by operating the sample tray shifting mechanism 6, the first sample tray located at the position A is pushed by the second sample tray and dropped down into the receiving container 7. The sample tray feeding apparatus repeats the above-mentioned operations consecutively. In this while, evaporation of water content from the samples 2 is prevented since they are kept in sealed condition owing to the protective cover and the sample trays mounted thereover. The sample tray feeding apparatus described above had a drawback that it functions to drop the sample trays 1 having been used for sample application into the receiving container 7 and therefore permitted no reuse of samples even when they are necessary for re-inspections etc. Moreover, the receiving container arranged between the sample adhering position and the sample applying position unavoidably prolonged the distance to be reserved between these positions, thereby requiring a long time to displace the blade 9 between the positions A and B. Accordingly, samples are dried after they are allowed to adhere to the balde until they are applied onto a carrier, thereby resulting in undesirable effects on analytical results.